Question: Solve for $k$ : $-8 + k = -16$
Answer: Add $8$ to both sides: $ \begin{eqnarray} \\ -8 + k &=& -16 \\ \\ {+8} && {+8} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-8 + k} &\hphantom{=}& \hphantom{-16} \\ k &=& -16 {+ 8} \\ \end{eqnarray} $ Simplify. $ k = -8$